Effect Of Chronic Ethanol Exposure And Withdrawal On The Synaptic Plasticity In Dorsal Striatum Of Rat

BACKGROUNDMany evidences demonstrated the establishment and development of addictive behavior involve learing and memory mechanism. Drug addiction represents the pathological usurpation of neural processes that normally serve reward-related learning. Memory and addiction share striking commonalities neural circuitry, neural plasticity, molecular and genomic mechanisms. Reward-guided behaviors are often attributed to the cortico-basal ganglia networks coursing through the neostriatum. The dorsal striatum has been proposed to contribute to the formation of habitual behavior including drug-seeking behaviors, leading to excessive and compulsive drug usage, such as addiction. Synaptic plasticty includes the plasticity of synaptic transmission efficency and synaptic connection, which means synaptic morphology. Long-term potentiation (LTP) enhances learning and long-term memory by strengthening the synapse, the point through which nervous impulses pass from one neuron to another.OBJECTIVETo investigate the effects of chronic ethanol intake and withdrawal on the synaptic plasticity in dorsal striatum of rats.METHODSRats were fed with ethanol for 10,20,30d and withdrawal 1,3,7d. Extracellular recording was used to test the changes of long-term potentiation(LTP) induced in slices of rat dorsal striatum and transmission electron microscopy(TEM) was used to observe the changes of synaptic ultrastructure.RESULTS1. Chronic ethanol exposure suppressed the induction of LTP to different extents in dorsal striatum, with the strongest suppressive effects on LTP occurring in 10d ethanol treated rats compared with control group.The depression was attenuated in 20d and 30d ethanol treated rats and notably, LTP was potentiated in withdrawl 7d rats.2. In the synaptic ultrastructure of dorsal striatum, the length of synaptic active zone was longer in withdrawal 7d rats ,while the width of synaptic cleft was narrower in 20d and 30d ethanol treated rats and the post synaptic density(PSD) was thinner in 30d ethanol treated rats than that of control.CONCLUSIONChronic ethanol exposure and withdrawal may result in the changes of the efficiency of synaptic transmission and the ability of synaptic connection in rat dorsal striatum.The effects may contribute to the establishment of habit behavior and relapse associated with alcoholism.